Full Idea
Although no semantic notions are used in Tarski's truth definitions themselves, they are used in deciding when such a definition is correct, namely the notion of translation.
Clarification
Tarski's truth definitions say that truth is just a relationship between parts of our language
Gist of Idea
Semantic notions do not occur in Tarski's definitions, but assessing their correctness involves translation
Source
Hilary Putnam (Representation and Reality [1988], §4 p.66)
Book Reference
Putnam,Hilary: 'Representation and Reality' [MIT 1992], p.66